The entire weekend we had miserable weather. It snowed, it sleeted, it hailed, it winded. After spending most of Saturday indoors, on Sunday we had enough and hauled a space heater out to the tarp covered wagon. We worked away in there, with a plentiful supply of tea, plotting the points that would form the circular shape of the walls.
A little about this approach to circles: Originally, we planned to use a "compass" made out of a pencil attached to a length of wire that was the length of the circle's radius, with the central point set at the spot that would be the circle's center. That would have worked fine for the front wall, but not the back wall, as the circle on the back changes depth halfway up. So instead we plotted the points of the circle on a graph and then transferred them to the boards. As you can see, it worked. But boy was that a lot of math.
Here's the nearly finished front wall at the end of the day, when it finally stopped precipitating.